| From 6eabb3301b1facee669d9938f7c5a0295c21d71d Mon Sep 17 00:00:00 2001 |
| From: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com> |
| Date: Mon, 13 May 2013 17:28:27 +0100 |
| Subject: ARM: 7720/1: ARM v6/v7 cmpxchg64 shouldn't clear upper 32 bits of the old/new value |
| |
| From: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com> |
| |
| commit 6eabb3301b1facee669d9938f7c5a0295c21d71d upstream. |
| |
| The implementation of cmpxchg64() for the ARM v6 and v7 architecture |
| casts parameter 2 and 3 (the old and new 64bit values) to an unsigned |
| long before calling the atomic_cmpxchg64() function. This clears |
| the top 32 bits of the old and new values, resulting in the wrong |
| values being compare-exchanged. Luckily, this only appears to be used |
| for 64-bit sched_clock, which we don't (yet) have on ARM. |
| |
| This bug was introduced by commit 3e0f5a15f500 ("ARM: 7404/1: cmpxchg64: |
| use atomic64 and local64 routines for cmpxchg64"). |
| |
| Acked-by: Will Deacon <will.deacon@arm.com> |
| Signed-off-by: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com> |
| Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm/include/asm/cmpxchg.h | 8 ++++---- |
| 1 file changed, 4 insertions(+), 4 deletions(-) |
| |
| --- a/arch/arm/include/asm/cmpxchg.h |
| +++ b/arch/arm/include/asm/cmpxchg.h |
| @@ -233,15 +233,15 @@ static inline unsigned long __cmpxchg_lo |
| ((__typeof__(*(ptr)))atomic64_cmpxchg(container_of((ptr), \ |
| atomic64_t, \ |
| counter), \ |
| - (unsigned long)(o), \ |
| - (unsigned long)(n))) |
| + (unsigned long long)(o), \ |
| + (unsigned long long)(n))) |
| |
| #define cmpxchg64_local(ptr, o, n) \ |
| ((__typeof__(*(ptr)))local64_cmpxchg(container_of((ptr), \ |
| local64_t, \ |
| a), \ |
| - (unsigned long)(o), \ |
| - (unsigned long)(n))) |
| + (unsigned long long)(o), \ |
| + (unsigned long long)(n))) |
| |
| #endif /* __LINUX_ARM_ARCH__ >= 6 */ |
| |
